For many years, fiber optic illumination systems have used fiber optic bundles to transmit light to industrial, dental and medical instruments. One end of the fiber optic bundle is conventionally inserted into an opening in a receptacle which is aligned with a light source. The light is transmitted through the fiber optic bundle to the instrument at the other end of the bundle.
In certain instances, it may be desirable to light two or more instruments at the same time. U.S. Pat. No. 3,638,013, for example, describes a fiber optic illumination system which is provided with a rotatable plug having three bundle-receiving openings. The plug may be rotated so that one, two or all three of the openings are positioned to be illuminated by a light source, whereby a corresponding number of instruments can be lit.
Various fiber optic illumination systems have been proposed in the past. Typically, these systems employ a lighting unit equipped with a light bulb, a concaved reflector and a fan for dissipating the heat generated by the bulb. Due to the large size of such a unit, it is usually located relatively far away from the work area. The remote positioning of the unit necessitates the use of relatively long fiber optic bundles (i.e., bundles as long as two to three meters). Due to the light losses inherent in fiber optic bundles, which losses can be as high as fifty percent per meter, the light bulb used must emit light of a high intensity, and, therefore, it must have a relatively high wattage (i.e., in the neighborhood of one hundred and fifty watts). One disadvantage of using high wattage bulbs is that they have a relatively short operating life. Another disadvantage is that the high emission of heat will inconvenience the operator as well as the patient. Furthermore, a relatively large fan must be used to cool the unit, the size of the fan creating an undesired increase in the overall size of the unit as well as producing disturbing noise.
In European patent application Serial No. PCT/SE82/00337, filed Oct. 18, 1982, there is disclosed a relatively compact fiber optic illumination system which includes a combination lens and reflector condensing system designed to concentrate light emitted from a relatively low wattage light bulb on a light-receiving end of a fiber optic bundle. Because its light is concentrated, the low wattage bulb can illuminate the light-receiving end of the fiber optic bundle to the same extent as a higher wattage light bulb. The use of a low wattage bulb is advantageous in that it takes up less room and generates less heat than a high wattage light bulb. However, in order to illuminate more than one fiber optic bundle and therefore more than one instrument, the lens of the condensing system is adapted so as to be switchable between two or more fiber optic bundles, whereby each fiber optic bundle may be selectively and independently coupled to the light bulb. Although the switch permits a plurality of fiber optic bundles to be illuminated, they can not be illuminated simultaneously. Also, the provision of such a light switch is disadvantageous because it requires a manual switching operation.